Television



May 4, 1943.

P. C. GOLDMARK TELEVISION Filed Feb. 24, 1941 2 Sheet's-Sheet 1 INVENTORPeze'r C Gold/warl- M Y izw ATTORNEYS May 4, 1943.

P. a GOLDMARK 2,317,989

TELEVISION Filed Feb; 24, 1941 2 Sheets-Sheet 2 INVENTOR Pezer C.Goldman? ATTORN EY5 Patented May 4, 1943 TELEVISION Peter C. Goldmark,New York, Y., assignor to Columbia, Broadcasting System, Inc., New York,N. Y., a corporation of New York Application February 24, 1941, SerialNo. 389,144 g 7 Claims.

This invention relates to television, especially to television innatural colors.

In an application entitled Television, filed concurrently herewith, JohnN. Dyer has disclosed apparatus for color television in which a movingendless band, such as a rotating drum, encircles part or all of ascanning device, thus facilitating the design and construction of acompact color television receiver.

The present application is directed mainly to the provision ofimprovements in the foregoing apparatus for facilitating the use ofrelatively small elements.

In accordance with one aspect of the invention, a cathode-ray receivertube is constructed with a bulbous portion having a luminescent screenat one end thereof and an elongated neck extending from the opposite endthereof at an angle with respect to the normal to the luminescentsurface. An electron gun structure is arranged within the elongated neckand the tube is provided with suitable deflecting means for causing thecathode ray to scan the luminescent screen. The rotating filter drum isarranged around the bulbous portion of the tube but does not encirclethe elongated neck. Thus the drum may be made smaller than would be thecase if it were required to encircle both the bulbous portion and theneck of the tube.

In one specific embodiment the elongated neck To insure proper phasingof the drum segments with respect to the scanning beam, and to furtherminimize the space required for the drum and its driving mechanism, theinvention provides a phonic motor having its armature secured directlyto the drum. In this manner, by originally assembling the armature andthe drum segments in proper phase relationship, subsequent correctphasing is insured.

The invention will be more fully understood by re erence to the specificembodiments illustrated in the drawings and the following descriptionthereof. In the drawings:

Fig. 1 is a front elevation of a specific embodiment of the invention;

Fig. 2 is a plan view thereof;

Figs. 3 and 4 are right and left side elevations, respectively, of theembodiment of Fig. 1; and

Figs. 5, 6 and '7 are plan, front and side views, respectively, ofanother specific embodiment.

Referring to Figs, 1-4, a cathode-ray receiver tube II is shown having abulbous portion I2 at one end of which is located 'a luminescent screenl3. In this specific embodiment the bulbous portion is approximatelycylindrical, but may be any other desired shape. At the other end of thebulbous portion, and toward one side thereof, extends an elongated neckl4 containing an electron gun structure IS. The electron beam from thisgun is deflected horizontally and vertically in the usual manner bysuitable deflecting means not shown). The dimensions of the tube and theangle which the elongated neck makes with the normal to the luminescentsurface are selected so that the cathode ray can scan the desiredscanning area 20 of the luminescent screen. Generally, the scanning area20 will be scanned in horizontal laterally extending sideby-side lines,interlaced or non-interlaced, at field scanning frequency, andsuccessive field scansions will correspond to successive colors.

Encircling the bulbous portions of the cathoderay tube is the drum i6having a plurality of different color filter segments ll arranged aroundthe peripheral surface thereof. For three-color reproduction one or moregroups of three red, green and blue filter segments may be employed. Inthe specific embodiment illustrated, twelve segments are employed, butthis number may be changed if desired.

The color filter drum I6 is rotated about the axis l8 by any suitabledriving means. specific embodiment illustrated, an asynchronous motor [9drives the drum through the belt 2| and supplies the main portion of thedriving power. In order to maintain the drum in proper synchronism withthe successively reproduced images, a phonic motor 22 is provided. Inaccordance with the present invention, the teeth 23 of the phonic motorare attached directly to the filter drum and project outwardlytherefrom. In the construction shown, a plate 25 forms one end of thefilter drum 26 and the ring of teeth 23 is secured thereto.

The number of teeth employed is selected to yield the desiredsynchronous speed. For example, with images reproduced at the rate of120 fields per second, and with a 120-cycle synchronizing wave suppliedto the phonic motor, 24 teeth will yield the proper synchronous speedfor a 12-segment drum. For other conditions, the number of teeth may bechanged in accordance with considerations well known in the art.

In the The synchronizing wave is supplied to the field coils of yokes2|, and may be obtained in any desired manner, for example, from thevertical synchronizing pulses or scanning wave. The specific embodimentshown employs a pair of yokes, but this number may be increased ifdesired.

By attaching the armature of the phonic motor directly to the filterdrum in proper orientation with respect to the filter segments, theproper phasing of the drum with respect to the scanning of the image isfacilitated.

It will be observed that by constructing the scanning tube so that theelongated neck extends at an angle with respect to the scanning area,the drum need encircle only the bulbous portion of the tube to be inproper position with respect to the scanning area. Thus the peripheralsurface of the drum may pass closely adjacent the scanning area andsubstantially parallel thereto (in the horizontal plane), and yet may beof smaller diameter than if it were required to encircle the entiretube. This permits a substantial saving in space in the receiver, aconsideration which is of considerable importance.

In operation, the number of segments of the drum and the circumferentiallength thereof may be selected as desired. For example, they may bechosen so that the filter segments traverse the scanning area in avertically (low frequency) direction at substantially the same speed asthat at which lines are scanned; Or, the height of the filter segmentsmay be made less than that of the scanning area, in accordance with theconsiderations disclosed in the application of John N. Dyer, supra; Ingeneral it is considered advantageous to orient the axis of the drum sothat the front edge of the drum extends generally parallel to thescanning area in a lateral direction, as shown in Fig. 2.

Referring now to the specific embodiments of Figs. -7, a cathode-rayreceiver tube 31 is shown having a bulbous portion 32, a fluorescentscreen 33 and an elongated neck 34 in which is positioned the electrongun 35. In this tube the neck is approximately at right angles withrespect to the normal to the fluorescent screen 33, and a coil 36 isprovided to bend the electrons in the scanning beam through an angle ofapproxi- .mately 90 so as to impinge on the fluorescent screen. Coil 36may be an electro-magnet energized by a suitable source of directcurrent, as desired. Defiecting and focussing coils 3! and .38 areprovided to cause the cathode-ray beam 39 to scan the fluorescent screenin the usual manner.

Encircling the bulbous portion of the cathoderay tube is drum 4| havingarranged around the peripheral surface thereof six color filter segmentscomprising two sets of red, green and blue filters denoted 42R, 42G and42B. Instead of six filter segments, twelve segments may be employed, orany other desired number.

It will be observed that by bending the neck at right angles to thenormal to the fluorescent surface, and by having the drum closelyencircle the tube, a very compact assembly is obtained, It will beunderstood that although the scanning area of the cathode-ray receivertube is commonly not flat, it is sufficiently close to being fiat sothat the term normal" can be employed with adequate clearness.

In the embodiment of Figs. 5-7 the neck projects beyond the boundariesor. confines of the drum in the axial direction, while in Figs. l-4 italso projects beyond theperipheral surface.

The operation of the apparatus of Figs. 5-7 is similar to that of Figs.1-4. It will be'understood that the number of colors, number ofsegments, speed of rotation, etc. may be chosen as desired in view ofthe particular scanning system employed.

It will be understood that the present invention is not limited to themere details ofconstruction and arrangement of the parts disclosed,since many modifications may be made by those skilled in the art withoutdeparting from the spirit and scope of the invention.

I claim:

1. In color television, apparatus which comprises an electronic scanningdevice comprising an envelope having a bulbous portion and an saidscanning area, said elongated neck extending beyond the boundaries ofsaid drum.

2. In color television, apparatus which comprises an electronic scanningdevice comprising an envelope having a bulbous portion and an elongatedneck extending therefrom, a two-dimensional scanning area positionedwithin said bulbous portion with the normal thereto at a substantialangle with respect to said neck, an electron gun structure within saidneck for generating an electron beam for scanning said area, and arotatable filter drum having a plurality of filter segments arrangedaround the peripheral surface thereof, said drum encircling said bulbousportion and being positioned so that as the drum rotates said filtersegments successively traverse said scanning area, the diameter of saiddrum being less than the length of said scanning device and saidelongated neck extending beyond the periphery of said drum.

3. In a color television receiver, apparatus which comprises acathode-ray receiver tube comprising an envelope having a bulbousportion and an elongated neck extending therefrom, a luminescent screenpositioned within said bulbous portion with the normal to the screen ata substantial angle with respect to said neck, an electron gun structureWithin said neck, means for scanning a two-dimensional area of saidscreen with an electron beam from said gun to reproduce images thereon,and a rotatable filter drum having a plurality of filter segmentsarranged around the peripheral surface thereof, said drum encirclingsaid bulbous portion and being positioned so that as the drum rotatessaid filter segments successively traverse said luminescent screen tothereby exhibit images thereon successively in difierent colors, saidelongated neck extending beyond the confines of said drum.

4. In a color television receiver, apparatus which comprises acathode-ray receiver tube comprising an envelope having a bulbousportion and an elongated neck extending therefrom, a luminescent screenpositioned within said bulbous portion with the normal to the screen ata substantial angle with respect to said neck, an electron gun structurewithin said neck, means for scanning a two-dimensional area of saidscreen with an electron "beam from said gun in a plurality ofside-by-side lines to reproduce images thereon, and a rotatablesubstantially cylindrical filter drum having a plurality of filtersegments arranged around the peripheral surface thereof, said drumencircling said bulbous portion and being positioned to rotate about anaxis substantially parallel with the image area so that said filtersegments successively traverse said scanning area, said elongated neckextending beyond the boundaries of said drum.

5. In a color television receiver, apparatus which comprises acathode-ray receiver tube comprising an envelope having a bulbousportion and an elongated neck extending therefrom, a luminescent screenpositioned within said bulbous portion with the normal to the screen ata substantial angle with respect to said neck, an electron gun structurewithin said neck, means for producing a magnetic field positionedbetween said electron gun and said screen to produce a substantiallyconstant angular deviation of the electron beam from said gun to causesaid beam to impinge the screen, means for deflecting said electron beamto scan a two-dimensional area of said screen to reproduce imagesthereon, and a rotatable filter drum having a plurality of filtersegments arranged around the peripheral surface thereof, said drumencircling said bulbous portion and being positioned so that as the drumrotates said filter segments successively traverse said luminescentscreen to thereby exhibit images thereon successively in differentcolors.

6. In color television, apparatus which comprises an electronic scanningdevice comprising an envelope having a bulbous portion and an elongatedneck extending therefrom, a two-dimensional scanning area positionedwithin said bulbous portion with the normal thereto at a substantialangle with respect to said neck, an electron gun structure within saidneck for generating an electron beam for scanning said area,

means for deflecting said electron beam to scan said scanning area in aplurality of laterally ex tending side-by-side lines, and a rotatablefilter drum having a plurality of filter segments arranged around theperipheral surface thereof, said drum encircling said bulbous portionand being positioned with the front edge thereof extending generallyparallel to said scanning area in a lateral direction so that as thedrum rotates said filter segments successively traverse said scanningarea in substantially the low-frequency direction, the diameter of saiddrum being less than the length of said scanning device and saidelongated neck extending beyond the periphery of said drum.

7. In a color television receiver, apparatus which comprises acathode-ray receiver tube comprising an envelope having a bulbousportion and an elongated neck extending therefrom, a luminescent screenpositioned within said bulbous portion adjacent the envelope thereofwith the normal to the screen at a substantial angle with respect tosaid neck, an electron gun structure within said neck, means forscanning a twodimensional area of said screen with an electron beam fromsaid gun in a plurality of laterally extending side by-side lines toreproduce images thereon, and a rotatable filter drum having a pluralityof filter segments arranged around the peripheral surface thereof, saiddrumencircling said bulbous portion and being positioned with the frontedge thereof extending generally parallel to said scanning area in alateral direction so that as the drum rotates said filter segmentssuccessively traverse said luminescent screen in substantially thelow-frequency direction to thereby exhibit images thereon successivelyin different colors, said elongated neck extending beyond the confinesof said drum.

' PETER o. GOLDMARK.

